Volcanology, structure, and stratigraphy of the central Sierra Nevada range front (California), Carson Pass to Sonora Pass

I use new geologic mapping, geochronological and geochemical data on Tertiary volcanic, volcaniclastic and intrusive rocks to investigate the volcanic, stratigraphic and structural evolution of the central Sierra Nevada, along the Sierran crest between Sonora Pass and Carson Pass. I used these techniques to unravel the fault history of Sierra Nevada frontal faults, including timing, magnitude of displacement, and possible structural controls on volcanism, such as siting of volcanic centers and types of edifices.;My work shows that fault displacement, coupled with major volcanism, initiated at or before 10.4 Ma at Sonora Pass and 6.3 Ma at Carson Pass. Previous workers estimated that fault displacement initiated at ∼ 3 Ma. Furthermore, the faults at Sonora Pass accommodated at least 2/3 of displacement before 10 Ma. Miocene magmas exploited these faults resulting in the formation of major volcanic edifices at right-steps on NNW normal faults and the development of smaller volcanic centers at intervening NNW normal faults and NE accommodation zones.;By mapping and defining four unconformity bounded sequences at Carson Pass, I reconstructed the local paleogeography and identified two paleotributaries that merged at the modern Sierran crest to form a single paleocanyon. These paleochannels were disrupted by two parallel normal faults that now bound the Hope Valley full graben. This graben controlled the siting of the 6 Ma Markleeville volcanic center.;At Sonora Pass, over half of the slip on N-S oriented down-to-the east normal faults occurred before and during eruption of the high-K Stanislaus Group at ∼10-11 Ma. The Little Walker Caldera, a proposed eruptive site for the high-K Table Mountain Latite, formed on a right-step in extensional normal faults.;Miocene volcanism in the central Sierra Nevada at Ebbetts Pass is dominated by the 10 Ma Stanislaus Group and the Late Miocene to Pliocene Ebbetts Pass stratovolcano. Geologic mapping and geochemical analyses enlarge the geographic extent of the high-K Stanislaus Group and indicate that range-front faults controlled the position of the basaltic andesite -- rhyolite Ebbetts Pass stratovolcano.